This is a good idea, especially for making parts for intro, verse and refrain. Yet their length is a problem, with your idea not.
But when you record a track not live, how does the switches happen. I have suggested containers that are busses for their embedded contraptions that fit to this function.
But here are these advantages:
-The Bus is ,like the drumscontraption, in the propertywindow. Means the main bus is still there for slow tweaks.
-Different contraptions can have different buslengths and switch possibilities.
-LFOs, envelopes are included
However your idea is simple and after all powerful. Live is your idea all I need